Researchers at Cornell University found eating fresh apples can keep dementia at bay, reports The Epoch Times. Apples are high in quercetin, a flavonoid that protects nerve cells against oxidative stress. It is believed that in Alzheimer’s Disease the brain over-produces beta-amyloid, a protein that makes free radicals and causes cumulative damage to brain cells. Quercetin, found in apple skin, mops up those free radicals. Red apples contain the highest concentration of quercetin.